Abstract 246: Evaluation of 2-Dimensional Aortic Arch Motion at the Origin of the Left Subclavian Artery: Importance of Respiratory Motion

Introduction: Interactions between components of branched thoracic main stent grafts (MSG) and branch stent grafts (BSG) in the arch have not yet been evaluated. As the chest is subject to both cardiac and respiratory motion, the purpose of this study is to evaluate the cardiac and respiratory effects on interactions between components in the aortic arch.

Methods: Two swine had a BSG alone placed in the LSA and two had an MSG/BSG system placed in the LSA. Frames representing the extreme positions of the BSG due to cardiac imposed motion during apnea and through the respiratory cycle were identified in 2-D cines. These images were overlaid as layers, using external reference markers common to each image for accurate overlay positioning. The BSG’s were traced and magnitudes of horizontal and vertical bulk displacements were quantified to evaluate cardiac (CM) and respiratory (RM) [deep inspiration (30 mmHg)]. Relative motion was extracted from bulk motion by comparing displacements at the top and bottom of the BSG.

Results: RM resulted in significant difference in bulk horizontal motion compared to CM for the BSG [5.65 + / - 0.07 versus 3.15 + / - 0.63mm, (p=0.002)] and was nearly significant for the MSG /BSG system [4.25 + / - 0.07 versus 2.3 + / - 0.42mm, (p=0.061)]. RM resulted in significant difference in bulk vertical movement compared to CM for the BSG [2.2 + / - 0.28 versus 0.85 + / - 0.35mm, (p=0.026)] and the MSG/BSG system [2.05 + / - 0.07 versus 0.6 + / - 0 (p=0.000001)]. The MSG presence significantly dampened bulk horizontal movement for RM [4.25 + / - 0.07 versus 5.65 + / - 0.07mm, (p=0.0013)] but had no effect on vertical movement [2.05 + / - 0.07 versus 2.2 + / - 0.28mm, (p=0.15)]. RM resulted in significant difference in relative horizontal motion compared to CM for the BSG [4.25 + / - 0.49 versus 2.7 + / - 0.28mm, (p=0.014)] and the MSG/BSG system [1.85 + / - 0.07 versus 0.95 + / - 0.35mm, (p=0.0048)]. RM resulted in significant difference in relative vertical movement compared to CM for the BSG [1.25 + / - 0.07 versus 0.3 + / - 0.28mm, (p=0.002)] and MSG/BSG system [0.7 + / - 0.14 versus 0.25 + / - 0.21mm, (p=0.03)]. The MSG presence significantly dampened relative horizontal and vertical movement for RM [1.85 + / - 0.07 versus 4.75 + / - 0.49mm, (p=0.0004)] and [0.7 + / - 0.14 versus1.25 + / - 0.07mm, (p=0.02)], respectively.

Conclusions: RM adds considerably to bulk and relative motion, with horizontal motion dominating. Relative motion accounts for high percentage of bulk motion. The presence of the MSG dampens motion considerably. This is the first study to account for the effects of respiratory motion on branched endografts in the aortic arch. This movement should be taken into account when developing a MSG/BSG for the therapy of aortic arch aneurysms.

A new technique for the surgical creation of aneurysms in an in vivo tortuous vessel model to test neurovascular devices

The purpose of this study was to develop an aneurysm model that mimics the tortuous anatomy of the cerebrovasculature for the evaluation of endovascular devices. This model is an adaptation of the carotid siphon model of Georganos et al. The common carotid artery trunks in 10 swine were surgically elongated using an EXXCEL Soft ePTFE vascular graft and then sutured into position to form an S-curve, with each bend having a 5- to 10-mm radius. Following a 3- to 4-week healing period, aneurysms were surgically created from jugular vein grafts along or distal to the tortuous segment and immediately embolized with coils. In a subset (n = 6) of the arteries, a stent was also placed across the aneurysm neck. Animals were allowed to survive for 30 days. Clinical relevance and utility of the model were evaluated based on comparison to human angiographic images, physician feedback, and histopathological assessment. Tortuous anatomy was successfully created in all 10 animals, and aneurysms were added at various locations within or distal to the tortuous segment in a subset of 8 animals, creating 11 aneurysms in total. At 30 days, 18/20 vessels were patent and the bend radius was maintained. Endovascular access to aneurysms and placement of embolization coils and/or stents was successful in 10 of 11 attempts. Physician feedback indicated this tortuous model was more clinically relevant in terms of endovascular device delivery and deployment compared to established, nontortuous aneurysm models.

ICP27-dependent resistance of herpes simplex virus type 1 to leptomycin B is associated with enhanced nuclear localization of ICP4 and ICP0

It was previously shown that herpes simplex virus type 1 (HSV-1) is sensitive to leptomycin B (LMB), an inhibitor of nuclear export factor CRM1, and that a single methionine to threonine change at residue 50 (M50T) of viral immediate-early (IE) protein ICP27 can confer LMB resistance. In this work, we show that deletion of residues 21-63 from ICP27 can also confer LMB resistance. We further show that neither the M50T mutation nor the presence of LMB affects the nuclear shuttling activity of ICP27, suggesting that another function of ICP27 determines LMB resistance. A possible clue to this function emerged when it was discovered that LMB treatment of HSV-1-infected cells dramatically enhances the cytoplasmic accumulation of two other IE proteins, ICP0 and ICP4. This effect is completely dependent on ICP27 and is reversed in cells infected with LMB-resistant mutants. Moreover, LMB-resistant mutations in ICP27 enhance the nuclear localization of ICP0 and ICP4 even in the absence of LMB, and this effect can be discerned in transfected cells. Thus, the same amino (N)-terminal region of ICP27 that determines sensitivity to LMB also enhances ICP27's previously documented ability to promote the cytoplasmic accumulation of ICP4 and ICP0. We speculate that ICP27's effects on ICP4 and ICP0 may contribute to HSV-1 LMB sensitivity.

Transactivation of a viral target gene by herpes simplex virus ICP27 is posttranscriptional and does not require the endogenous promoter or polyadenylation site

ICP27 is an essential herpes simplex virus type 1 (HSV-1) immediate-early protein that stimulates viral mRNA expression from many viral delayed-early and late genes during infection. One HSV-1 late gene which is highly dependent on ICP27 during infection is that encoding the glycoprotein C (gC). Here we report that the gC gene is specifically transactivated by ICP27 in transfected Vero cells. Using various gC plasmid constructs, we show that ICP27's stimulatory effects are independent of the gC gene's endogenous promoter and polyadenylation site. This suggests that ICP27-responsive elements lie in the transcribed body of the gC gene. We also show that transactivation of the gC gene by ICP27 is independent of other viral proteins, as ICP27 alone can transactivate the gC gene when its transcription is mediated by the human cytomegalovirus immediate-early gene promoter. However, when gC gene expression is driven by its endogenous promoter, the stimulatory effect of ICP27 requires additional transactivators. To explore the level at which ICP27 transactivates the gC gene, we established stably transfected Vero cell lines that have integrated copies of the gC gene under control of the cytomegalovirus immediate-early gene promoter. These gC genes are not constitutively expressed but can be efficiently induced by HSV-1 infection. Using nuclear run-on transcription assays, we show that transcriptional induction of the stably transfected genes is ICP27 independent. In contrast, accumulation of gC mRNA is very highly dependent on ICP27. Together, these results demonstrate that ICP27 posttranscriptionally activates mRNA expression from a biologically relevant viral target gene.

Angiotensin type 1 receptor antagonism with irbesartan inhibits ventricular hypertrophy and improves diastolic function in the remodeling post-myocardial infarction ventricle

To evaluate the role of angiotensin II (AII) on diastolic function during post-myocardial infarction (MI) ventricular remodeling, coronary ligation or sham operation was performed in male Sprague-Dawley rats. Experimental animals were maintained on either irbesartan, a selective AT1-receptor antagonist, or no treatment. Measurement of cardiac hypertrophy, diastolic function, and sarcoendoplasmic reticulum adenosine triphosphatase (ATPase; SERCA) and phospholamban (PLB) gene expression was assessed at 6 weeks after MI. Myocardial infarction caused a significant increase in myocardial mass and left ventricular (LV) filling pressure, whereas LV systolic pressure and +dP/dt were reduced. The time constant of isovolumic relaxation (tau) was markedly prolonged after MI. Post-MI hypertrophy was associated with substantial increases in the messenger RNA (mRNA) expression of atrial natriuretic peptide (ANP), but no significant changes in SERCA or PLB levels. Although irbesartan treatment did not significantly alter post-MI LV systolic or filling pressures, it nevertheless effectively decreased ventricular hypertrophy, improved tau, and normalized ANP expression. These results demonstrate that AT1-receptor antagonism has important effects on myocardial hypertrophy and ANP gene expression, which are independent of ventricular loading conditions. In addition, the improvement in diastolic function was not related to changes in SERCA and PLB gene expression, suggesting that enhanced myocardial relaxation was related to the blockade of AII effects on myocyte function or through a reduction of ventricular hypertrophy itself or both.

The Association of Severe Epidemics of Cucumber Mosaic in Commercial Fields of Pepper and Tobacco in North Florida with Inoculum in Commelina benghalensis and C. communis

Since 1995, severe epidemics of cucumber mosaic virus (CMV) have occurred in select fields of tobacco (Nicotiana tabacum) and pepper (Capsicum annuum) in three counties in northern Florida. Yield losses greater than 50% have occurred in both crops. Baker and Zettler (1) identified the presence of CMV in one plant of tropical spiderwort (Commelina benghalensis) in an organic garden on the campus of the University of Florida 10 years ago. In addition, they infected tropical spiderwort and Asiatic dayflower (Commelina communis) with isolates of CMV. Since 1995, in one area of northern Alachua County, Asiatic dayflower has been found in abundance in and around some fields and found to be infected with CMV. Prior to this time, CMV had not been known to be epidemic in any crop in northern Florida. Also, commelinaceous weeds did not occur in such abundance in northern Florida. In Hamilton County, an epidemic of CMV occurred in one field of tobacco in 1997. Tropical spiderwort with viral-like symptoms was growing abundantly in that field. The symptoms in this weed included chlorotic ringspots and chevron-like line patterns. Light microscopy, with Azure A stain, revealed the presence of typical inclusions of CMV in pepper, tobacco, tropical spiderwort, and Asiatic dayflower. Symptomatic samples of the tobacco and the tropical spiderwort reacted in an immunodiffusion test with antiserum to a winged bean isolate of CMV (2). Extracts from tropical spiderwort (isolate 3603) were rubbed on squash. This isolate was thereafter maintained in squash (Cucurbita pepo cvs. Prelude II or Early Prolific Straightneck). Infected plants of both of these cultivars developed strong mosaic symptoms and were stunted. After passage through squash, the 3603 isolate induced mosaic in tobacco (cv. Burley 21). Some plants of the squash cultivars Destiny III and Liberator III, which have transgenic, coat protein-mediated resistance to CMV, developed restricted symptoms after inoculation with this isolate. CMV was recovered by back inoculation from symptomatic plants of these cultivars. Symptomless plants of tropical spiderwort transplanted from the field developed chlorotic ringspots and chevron-like line patterns following inoculation in the greenhouse with isolate 3603. Back inoculations to squash followed by immunodiffusion assays confirmed the presence of CMV in the inoculated tropical spiderwort plants but CMV was not detected in noninoculated control plants. This is the first report of tropical spiderwort being infected with CMV in a commercial situation in the United States. Because commelinaceous plants are well known to be excellent hosts of CMV (1), we believe that the increased presence of perennial, commelinaceous weeds is a factor contributing to the epidemics of CMV in northern Florida. References: (1) C. A. Baker and F. W. Zettler. Plant Dis. 72:513, 1988. (2) C. A. Ku-wite and D. E. Purcifull. Plant Dis. 66:1071, 1982.

Alveolar soft-part sarcoma in the oral cavity: report of a case

This case presents a rare tumor of the oral cavity--an alveolar soft-part sarcoma. Difficulties developed in the diagnosis, and therefore, consultations were required. Because of the radioresistant qualities of the lesion, wide surgical excision was performed. The patient's condition has been followed for 40 months without evidence of recurrence. The conclusion arrived at from review of the literature is that this is an indolent but malignant tumor and has so far proved to be 100% fatal. However, it may be 20 years before it proves fatal.